我们都知道太阳系是以太阳为中心的，和所有受到太阳的引力约束天体的集合体。包括八大行星（由离太阳从近到远的顺序：水星、金星、地球、火星、木星、土星、天王星、海王星），而我用html和css所写的就是八大行星和太阳组成的星系，比较简易，代码如下：<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.softwhy.com/" />
<title></title>
<style>
* {
  padding: 0;
  margin: 0;
}
body {
  width: 100%;
  height: 100%;
  background-color: #9370DB;
}
ul {
  height: 600px;
  width: 600px;
  margin: 50px auto;
  list-style: none;
  /* background: red; */
}
ul li {
    /* 在页面的中间呈现 */
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
  border: 2px solid #D3D3D3;
}
/* 最中间圆的设置--太阳 */
li:nth-child(1) {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  /* 设置阴影 */
  box-shadow: 0 0 50px #FAFF27;
  background-color: #FAFF27;
}
/* 设置第二个轨道线 */
li:nth-child(2) {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  /* animation简写：名称 时间 速度（下面设置的速度从头到尾相同） 播放次数（此为无限） */
  animation: rotate 30s linear infinite;
}
/* 水星设置 */
li:nth-child(2) span {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background-color: deepskyblue;
  position: absolute;
  top: 0;
  left: 25px;
}
li:nth-child(3) {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  animation: rotate 20s linear infinite;
}
/* 金星 */
li:nth-child(3) span {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background-color: gold;
  position: absolute;
  top: 0;
  left: 35px;
}
li:nth-child(4) {
  width: 240px;
  height: 240px;
  border-radius: 50%;
  animation: rotate 20s linear infinite;
}
/* 地球 */
li:nth-child(4) > span {
  width: 25px;
  height: 25px;
  border-radius: 50%;
  background-color: #6dff39;
  position: absolute;
  top: 0;
  left: 135px;
  animation: rotate 10s linear infinite;
}
/* 月亮 */
li:nth-child(4) > span span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background-color: #ff40c0;
  position: absolute;
  top: 0;
  left: 30px;
}

li:nth-child(5) {
  width: 300px;
  height: 300px;
  border-radius: 50%;
  animation: rotate 10s linear infinite;
}
/* 火星 */
li:nth-child(5) span {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background-color: red;
  position: absolute;
  top: 0;
  left: 90px;
}
li:nth-child(6) {
  width: 360px;
  height: 360px;
  border-radius: 50%;
  animation: rotate 30s linear infinite;
}
/* 木 */
li:nth-child(6) span {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background-color: burlywood;
  position: absolute;
  top: 0;
  left: 100px;
}
li:nth-child(7) {
  width: 420px;
  height: 420px;
  border-radius: 50%;
  animation: rotate 40s linear infinite;
}
/* 土 */
li:nth-child(7) > span {
  width: 25px;
  height: 25px;
  border-radius: 50%;
  background-color: brown;
  position: absolute;
  top: 0;
  left: 190px;
  animation: rotate 15s linear infinite;
}

li:nth-child(8) {
  width: 480px;
  height: 480px;
  border-radius: 50%;
  animation: rotate 10s linear infinite;
}
/* 天王 */
li:nth-child(8) span {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background-color: #3f8042;
  position: absolute;
  top: 0;
  left: 175px;
}
li:nth-child(9) {
  width: 540px;
  height: 540px;
  border-radius: 50%;
  animation: rotate 20s linear infinite;
}
li:nth-child(9) span {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background-color: #0000FF;
  position: absolute;
  top: 0;
  left: 175px;
}
/* 关键帧 */
@keyframes rotate {
  0% {
    transform: translate(-50%,-50%) rotate(0deg);
  }
  100% {
    transform: translate(-50%,-50%) rotate(360deg);
  }
}
</style>
</head>
<body>
  <ul>
    <li></li>
    <li><span></span></li>
    <li><span></span></li>
    <li><span><span></span></span></li>
    <li><span></span></li>
    <li><span></span></li>
    <li><span><span></li>
    <li><span></span></li>
    <li><span></span></li>
  </ul>
</body>
</html>